3 measured metrics · 3 calculated · 2 studies
Claude Opus 5.5lowvsmediumeffort
“default”: the effort flag was not passed and the CLI chose.
No row separates them: 1 tie, 5 unclear.
The verdict
Claude Opus 5.5 at low effort and Claude Opus 5.5 at medium effort share 3 measured metrics and 3 list-price calculations from 2 studies. Only the effort setting differs between the two sides of a row; the route and the task set are the same. No row separates them: every interval or run range overlaps, too few runs were recorded, no interval was recorded, or more is not better for that metric. The rows are 1 tie and 5 unclear; each row says why. Calculation rows are derived from list prices and recorded counts; they are not bills or runs.
Headline metrics
How far apart the two sides are on the headline metrics. Length is the ratio of the two values; it is not a winner.
Bar length is the ratio of the two values on a log scale, pointing to the larger one. Larger is not better for time, tokens or cost. A bar has a side’s color only when that side is ahead in the data; gray means the data does not separate them.
| Metric | Claude Opus 5.5 at low effort | Claude Opus 5.5 at medium effort | n | Interval or range | Outcome | Basis | Study |
|---|---|---|---|---|---|---|---|
| Strict pass rate by effort on eight hard tasks | 100% (16/16)Claude Code · effort low · eight hard validated tasks, effort ladder | 100% (16/16)Claude Code · effort medium · eight hard validated tasks, effort ladder | 16 | 95% CI: 81%–100% vs 81%–100% | Tie | The 95% intervals overlap (Claude Opus 5.5 at low effort 81% to 100%; Claude Opus 5.5 at medium effort 81% to 100%), so this sample cannot separate them. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
| Total time per call by effort on hard tasks | 7.50 sClaude Code · effort low · eight hard validated tasks, effort ladder | 9.72 sClaude Code · effort medium · eight hard validated tasks, effort ladder | 16 | range: 3.3 s–15.8 s vs 4.8 s–31.4 s | Unclear | The run ranges (fastest to slowest) overlap (Claude Opus 5.5 at low effort 3.34 s to 15.8 s; Claude Opus 5.5 at medium effort 4.78 s to 31.4 s); the medians alone do not show a reliable difference. A range is not a confidence interval. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
| Output tokens per call by effort on hard tasks (Output tokens) | 594Claude Code · effort low · eight hard validated tasks, effort ladder | 853Claude Code · effort medium · eight hard validated tasks, effort ladder | 16 | none recorded | Unclear | More or fewer tokens is not better or worse by itself; this row describes behaviour, not a winner. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
| List-price cost per strict pass by effort (calculation)Calculation | $0.021Claude Code · effort low · eight hard validated tasks, effort ladder | $0.029Claude Code · effort medium · eight hard validated tasks, effort ladder | 16 | none recorded | Unclear | No interval or range was recorded for either side, so the gap ($0.021 vs $0.029) is not tested against run-to-run variation. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
Marks: 95% intervals (Wilson for rates); fastest–slowest run ranges (not intervals)n is shown per side on every rowHollow marks: list-price calculations, not runs
4 headline metrics as the ratio of the two values. None of them separates the sides in the data. Widest ratio: Output tokens per call by effort on hard tasks (Output tokens), 1.4x (Medium effort larger).
Watch it build
A live story drawn from the same dataset in your browser. It shows the same numbers, notes and interval labels as this page.
Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on eight hard tasks
All 11 configurations passed 16/16 strictly (95% interval 81%–100%): more effort bought no extra passes on this set (a ceiling). Median output tokens rose with effort; time ranges overlap. Costs are list-price calculations.
Transcript
- Effort ladder · 176 calls · 11 configurations. Does more effort buy quality? Low, medium and high effort on eight hard tasks. Sonnet 5.5 and Opus 5.5 via Claude Code, GPT-6.1 Sol via Codex CLI.
- 176 of 176 calls passed strictly, at every effort level. No format misses and no wrong answers. Calls that passed strictly, every effort: 100% (176/176) (n = 176, 95% CI 98–100%). Model and effort configurations: 11 (6 new, 5 reference) (n = 176). Format misses and wrong answers: 0 · 0 (n = 176, format · wrong). Caveat: Reference cells ran in a different batch and hour than the new cells (provider load can differ), on the same host, CLI versions, cases and flags.
- All 11 configurations passed 16/16. A 16/16 has a 95% interval of 81%–100%: the set has a ceiling, so no effort level wins. Chart: Strict pass rate by effort · 95% Wilson intervals (n = 16 each). Caveat: Every cell passed every call, so the set has a ceiling: a perfect 16/16 has a 95% interval of 81% to 100%. This study cannot show that effort does not matter on harder work; it shows that these 8 tasks do not need more than low effort.
- Median time: Sonnet 5.5 5.8 s at low, 8.8 s at high; Opus 5.5 7.5 s at low, 10.1 s at high; GPT-6.1 Sol 13.6 s at low, 18.1 s at high. Within each model the ranges overlap: no effort is ranked faster. Chart: Median total time per call · whiskers: fastest to slowest call (n = 16 each). Caveat: Each cell has only 2 calls per task. Medians of 16 calls move with a few slow calls; the ranges are wide and overlap.
- More effort writes more: Sonnet 5.5 used a median 667 / 770 / 1,192 output tokens at low / medium / high. Chart: Median output and reasoning tokens per call (n = 16 each). Caveat: Claude Code and Codex CLI rows pair a CLI with a model; each CLI adds its own system prompt and start-up time. Effort levels are not the same scale across vendors.
- List-price cost per strict pass, low → high effort, a calculation: Sonnet $0.0122 → $0.0167, Opus $0.0212 → $0.0337, GPT-6.1 Sol $0.0128 → $0.0151. Chart: List-price cost per strict pass · calculation (n = 16 each). Calculation, not a run. Caveat: List-price costs are calculations; the calls used flat subscriptions.
- 16 effort pairs, 172 comparison rows: no effort level wins any row. The rest are ties or unclear. Effort pairs compared (same model, same route): 16. Comparison rows across those pairs: 172. Rows where one effort level wins: 0 (of 172). Caveat: Every cell passed every call, so the set has a ceiling: a perfect 16/16 has a 95% interval of 81% to 100%. This study cannot show that effort does not matter on harder work; it shows that these 8 tasks do not need more than low effort.
- Start at low effort and measure. Every call, interval and cost online.
Metric by metric
Both values of a row come from the same chart in the same study. Each row has its own axis. The shaded band is where the two intervals or ranges overlap: a side is ahead only when they do not.
- Low effort
- Medium effort
- 95% interval
- fastest–slowest run (not an interval)
- where the two overlap
- hollow: list-price calculation
Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks
- Strict pass rate by effort on eight hard tasks100% (16/16)n 16100% (16/16)n 16TieStrict pass rate by effort on eight hard tasks: Low effort 100% (16/16) (n 16, 95% interval 81%–100%); Medium effort 100% (16/16) (n 16, 95% interval 81%–100%). Tie.
- Total time per call by effort on hard tasks7.50 sn 169.72 sn 16UnclearTotal time per call by effort on hard tasks: Low effort 7.50 s (n 16, run range 3.3 s–15.8 s); Medium effort 9.72 s (n 16, run range 4.8 s–31.4 s). Unclear.
- Output tokens per call by effort on hard tasks (Output tokens)594n 16853n 16UnclearOutput tokens per call by effort on hard tasks (Output tokens): Low effort 594 (n 16); Medium effort 853 (n 16). Unclear.
- List-price cost per strict pass by effort (calculation)Calculation$0.021n 16$0.029n 16UnclearList-price cost per strict pass by effort (calculation), calculation: Low effort $0.021 (n 16); Medium effort $0.029 (n 16). Unclear.
How much of an AI bill is thinking? Reasoning tokens by model and effort
- Reasoning cost per strict pass by effort, with the total (calculation) (Reasoning cost per strict pass)Calculation$0.0050n 16$0.013n 16UnclearReasoning cost per strict pass by effort, with the total (calculation) (Reasoning cost per strict pass), calculation: Low effort $0.0050 (n 16); Medium effort $0.013 (n 16). Unclear.
- Reasoning cost per strict pass by effort, with the total (calculation) (Total cost per strict pass)Calculation$0.021n 16$0.029n 16UnclearReasoning cost per strict pass by effort, with the total (calculation) (Total cost per strict pass), calculation: Low effort $0.021 (n 16); Medium effort $0.029 (n 16). Unclear.
| Metric | Claude Opus 5.5 at low effort | Claude Opus 5.5 at medium effort | n | Interval or range | Outcome | Basis | Study |
|---|---|---|---|---|---|---|---|
| Strict pass rate by effort on eight hard tasks | 100% (16/16)Claude Code · effort low · eight hard validated tasks, effort ladder | 100% (16/16)Claude Code · effort medium · eight hard validated tasks, effort ladder | 16 | 95% CI: 81%–100% vs 81%–100% | Tie | The 95% intervals overlap (Claude Opus 5.5 at low effort 81% to 100%; Claude Opus 5.5 at medium effort 81% to 100%), so this sample cannot separate them. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
| Total time per call by effort on hard tasks | 7.50 sClaude Code · effort low · eight hard validated tasks, effort ladder | 9.72 sClaude Code · effort medium · eight hard validated tasks, effort ladder | 16 | range: 3.3 s–15.8 s vs 4.8 s–31.4 s | Unclear | The run ranges (fastest to slowest) overlap (Claude Opus 5.5 at low effort 3.34 s to 15.8 s; Claude Opus 5.5 at medium effort 4.78 s to 31.4 s); the medians alone do not show a reliable difference. A range is not a confidence interval. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
| Output tokens per call by effort on hard tasks (Output tokens) | 594Claude Code · effort low · eight hard validated tasks, effort ladder | 853Claude Code · effort medium · eight hard validated tasks, effort ladder | 16 | none recorded | Unclear | More or fewer tokens is not better or worse by itself; this row describes behaviour, not a winner. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
| List-price cost per strict pass by effort (calculation)Calculation | $0.021Claude Code · effort low · eight hard validated tasks, effort ladder | $0.029Claude Code · effort medium · eight hard validated tasks, effort ladder | 16 | none recorded | Unclear | No interval or range was recorded for either side, so the gap ($0.021 vs $0.029) is not tested against run-to-run variation. | Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks |
| Reasoning cost per strict pass by effort, with the total (calculation) (Reasoning cost per strict pass)Calculation | $0.0050Claude Code · effort low | $0.013Claude Code · effort medium | 16 | none recorded | Unclear | More or fewer usd is not better or worse by itself; this row describes behaviour, not a winner. | How much of an AI bill is thinking? Reasoning tokens by model and effort |
| Reasoning cost per strict pass by effort, with the total (calculation) (Total cost per strict pass)Calculation | $0.021Claude Code · effort low | $0.029Claude Code · effort medium | 16 | none recorded | Unclear | More or fewer usd is not better or worse by itself; this row describes behaviour, not a winner. | How much of an AI bill is thinking? Reasoning tokens by model and effort |
Marks: 95% intervals (Wilson for rates); fastest–slowest run ranges (not intervals)n is shown per side on every rowHollow marks: list-price calculations, not runs
6 rows from 2 studies. No row separates them: 1 tie, 5 unclear.
When to pick which
Only from the rows above. A tie is not a reason to pick either side.
When to pick Claude Opus 5.5 at low effort
- Reasoning cost per strict pass by effort, with the total (calculation) (Reasoning cost per strict pass): $0.0050 vs $0.013. A list-price calculation, not a measured difference. Calculation
When to pick Claude Opus 5.5 at medium effort
No row in this data puts Claude Opus 5.5 at medium effort ahead of Claude Opus 5.5 at low effort. Pick on other grounds (price, access, the tasks you run), or measure your own workload.
Side by side
The study charts, showing only Claude Opus 5.5 at each effort it ran; the two compared settings are highlighted. Open a study for every configuration.
Every interval overlaps every other: this chart does not order these rows.
| Item | Strict pass | 95% interval | n |
|---|---|---|---|
| Claude Opus 5.5 (low) · Claude Code | 100% | 81%–100% | 16 |
| Claude Opus 5.5 (medium) · Claude Code | 100% | 81%–100% | 16 |
| Claude Opus 5.5 (high) · Claude Code | 100% | 81%–100% | 16 |
| Claude Opus 5.5 · Claude Code | 100% | 81%–100% | 16 |
4 rows. All at 100%.
NotesWhiskers: 95% Wilson intervaln = 16 per row4 of 4 at 100%: this task set cannot separate them.
Every configuration: 8 tasks × 2 repetitions. Whiskers are 95% Wilson intervals
Whiskers are 95% Wilson intervals. A format miss never counts as a pass. Reference cells (efforts the hard head-to-head already ran) are reused, not rerun; Claude reference cells keep repetitions 1-2, so every cell is 8 tasks × 2 repetitions.
Source: Effort ladder: the hard task set at each effort level
Every lane’s run range overlaps another lane’s, so the chart shows no finish order.
| Item | Total time per call by effort on hard tasks | Range (lowest–highest run) | n |
|---|---|---|---|
| Claude Opus 5.5 (low) · Claude Code | 7.5 s | 3.3 s–15.8 s | 16 |
| Claude Opus 5.5 (medium) · Claude Code | 9.7 s | 4.8 s–31.4 s | 16 |
| Claude Opus 5.5 (high) · Claude Code | 10.1 s | 3.6 s–63 s | 16 |
| Claude Opus 5.5 · Claude Code | 9.2 s | 4.2 s–27.2 s | 16 |
4 rows. Slowest Claude Opus 5.5 (high) · Claude Code 10.1 s (range 3.6 s–63 s, n 16). Fastest Claude Opus 5.5 (low) · Claude Code 7.5 s (range 3.3 s–15.8 s, n 16). All run ranges overlap.
NotesLines: fastest–slowest run (not an interval)n = 16 per row
Median per configuration; whiskers = fastest and slowest call
Whiskers are a range (fastest and slowest call), not a confidence interval. One host, one network. Reference cells (efforts the hard head-to-head already ran) are reused, not rerun; Claude reference cells keep repetitions 1-2, so every cell is 8 tasks × 2 repetitions. The reference cells ran in a different hour.
Source: Effort ladder: the hard task set at each effort level
| Item | Output tokens | n |
|---|---|---|
| Claude Opus 5.5 (low) · Claude Code | 594 | 16 |
| Claude Opus 5.5 (medium) · Claude Code | 853 | 16 |
| Claude Opus 5.5 (high) · Claude Code | 1,052 | 16 |
| Claude Opus 5.5 · Claude Code | 945 | 16 |
4 rows. Highest Claude Opus 5.5 (high) · Claude Code 1,052 (n 16). Lowest Claude Opus 5.5 (low) · Claude Code 594 (n 16).
Notesn = 16 per row
Median per configuration; reasoning tokens as the CLI reports them
Reasoning tokens are part of the output tokens where the CLI reports them; 0 can mean "not reported". Their content is never captured. More tokens is not better or worse by itself.
Source: Effort ladder: the hard task set at each effort level
Hover or focus a bar for its ratio to Claude Opus 5.5 (low) (the lowest value): a ratio of list-price calculations, not a measurement.
| Item | Cost per strict pass | n |
|---|---|---|
| Claude Opus 5.5 (low) · Claude Code | $0.021 | 16 |
| Claude Opus 5.5 (medium) · Claude Code | $0.029 | 16 |
| Claude Opus 5.5 (high) · Claude Code | $0.034 | 16 |
| Claude Opus 5.5 · Claude Code | $0.029 | 16 |
List-price calculation, not a run. 4 rows. Highest Claude Opus 5.5 (high) · Claude Code $0.034 (n 16). Lowest Claude Opus 5.5 (low) · Claude Code $0.021 (n 16).
Notesn = 16 per row
All calls in a configuration divided by its strict passes
Calculation, not a bill: reported tokens × list price, cache reads and writes priced as in the hard head-to-head; the calls ran on flat subscriptions. Codex input includes its own system prompt and tool schemas, so a Claude-vs-Codex gap is partly the CLI.
Sources: Effort ladder: the hard task set at each effort level, Repricing calculation, Anthropic list prices (Claude models), OpenAI list prices
- Reasoning cost per strict pass
- Total cost per strict pass (square)
Gap labels, Total cost per strict pass vs Reasoning cost per strict pass: Total cost per strict pass is x% higher (+) or lower (−) than Reasoning cost per strict pass, calculated from the two values shown (the change counted from Reasoning cost per strict pass’s value).
| Item | Reasoning cost per strict pass | Total cost per strict pass | n |
|---|---|---|---|
| Claude Opus 5.5 (low) · Claude Code | $0.005 | $0.021 | 16 |
| Claude Opus 5.5 (medium) · Claude Code | $0.013 | $0.029 | 16 |
| Claude Opus 5.5 (high) · Claude Code | $0.018 | $0.034 | 16 |
| Claude Opus 5.5 · Claude Code | $0.013 | $0.029 | 16 |
List-price calculation, not a run. 4 rows, 2 series: Reasoning cost per strict pass, Total cost per strict pass. Reasoning cost per strict pass: highest Claude Opus 5.5 (high) · Claude Code $0.018 (n 16). Lowest Claude Opus 5.5 (low) · Claude Code $0.005 (n 16). Total cost per strict pass: highest Claude Opus 5.5 (high) · Claude Code $0.034 (n 16). Lowest Claude Opus 5.5 (low) · Claude Code $0.021 (n 16).
Notesn = 16 per row
List price ÷ strict passes; every cell is 8 tasks × 2 repetitions
Calculation, not a bill: reported tokens × list price, divided by the cell's strict passes; the calls ran on flat subscriptions. The effort-ladder cells: new calls plus reference cells reused from the hard head-to-head (Claude repetitions 1-2 only). "Default" means the effort flag was not passed. The total is the same value as the effort-ladder cost-per-pass chart. Effort levels are not the same scale across vendors, and the reference cells ran in a different batch and hour.
Sources: Reasoning token bill (calculation), Provider head-to-head, hard set: eight hard tasks with strict validators, Effort ladder: the hard task set at each effort level, Provider head-to-head: Claude Code models vs Codex efforts, Anthropic list prices (Claude models), OpenAI list prices
How a row is called
- AheadThe 95% intervals do not overlap, or the run ranges or p50–p95 bands do not overlap with at least 5 runs per side.
- TieThe values match, or both sit at the same ceiling.
- UnclearThe intervals or ranges overlap, too few runs were recorded, no interval was recorded, or more is not better (token counts are never a win).
- CalculationDerived from list prices and recorded counts. Not a bill and not a run.
The dataset compiler makes every call; this page only draws it. No composite score, no rank.
Questions
- Is Claude Opus 5.5 better at low effort or medium effort?
- Claude Opus 5.5 at low effort and Claude Opus 5.5 at medium effort share 3 measured metrics and 3 list-price calculations from 2 studies. Only the effort setting differs between the two sides of a row; the route and the task set are the same. No row separates them: every interval or run range overlaps, too few runs were recorded, no interval was recorded, or more is not better for that metric. The rows are 1 tie and 5 unclear; each row says why. Calculation rows are derived from list prices and recorded counts; they are not bills or runs.
- How were the two effort settings measured?
- They share 3 measured metrics and 3 list-price calculations from 2 public studies: Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks; How much of an AI bill is thinking? Reasoning tokens by model and effort. Only the effort setting differs between the two sides of a row.
- How does strict pass rate by effort on eight hard tasks change from low effort to medium effort?
- Claude Opus 5.5 at low effort: 100% (16/16) (n = 16, 95% interval 81% to 100%). Claude Opus 5.5 at medium effort: 100% (16/16) (n = 16, 95% interval 81% to 100%). The 95% intervals overlap (Claude Opus 5.5 at low effort 81% to 100%; Claude Opus 5.5 at medium effort 81% to 100%), so this sample cannot separate them.
- How does total time per call by effort on hard tasks change from low effort to medium effort?
- Claude Opus 5.5 at low effort: 7.50 s (n = 16, run range 3.3 s to 15.8 s). Claude Opus 5.5 at medium effort: 9.72 s (n = 16, run range 4.8 s to 31.4 s). The run ranges (fastest to slowest) overlap (Claude Opus 5.5 at low effort 3.34 s to 15.8 s; Claude Opus 5.5 at medium effort 4.78 s to 31.4 s); the medians alone do not show a reliable difference. A range is not a confidence interval.
The studies behind this page
Does more effort buy quality? Sonnet, Opus and GPT-6.1 Sol on 8 hard tasks
176 calls on 8 hard tasks at low, medium, high and default effort: Sonnet, Opus and GPT-6.1 Sol. Pass rate with 95% intervals, time, tokens, cost per pass.
How much of an AI bill is thinking? Reasoning tokens by model and effort
Reasoning tokens in 378 recorded calls by model and effort: share of output, list-price cost per call and per pass, and time. Calculations.